153 lines
4 KiB
OpenEdge ABL
153 lines
4 KiB
OpenEdge ABL
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/*
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Copyright (c) Microsoft Corporation. All rights reserved.
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*/
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#ifndef _MSPENUM_H_
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#define _MSPENUM_H_
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//////////////////////////////////////////////////////////////////////////////
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//
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// CSafeComEnum
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//
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// All TAPI 3.0 system components and MSPs use the CSafeComEnum class instead
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// of ATL 2.1's CComEnum class when implementing enumerator objects that are
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// accessible to applications. This is needed for the following reasons:
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//
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// 1. CComEnum does not perform IsBadWritePtr checks on the pointer arguments
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// to the enumerator methods. This allows the component exposing the
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// enumerator to AV when called with invalid pointer arguments.
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//
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// 2. CComEnum does not support free thread marshaling, and therefore cannot
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// be used from an apartment threaded application.
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//
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// Note: No debug tracing is done here, to facilitate use of this template
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// independent of the rest of the MSP Base Classes.
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//
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/////////////////////////////////////////////////////////////////////////////
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template <class Base, const IID* piid, class T, class Copy,
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class ThreadModel = CComObjectThreadModel>
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class ATL_NO_VTABLE CSafeComEnum :
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public CComEnumImpl<Base, piid, T, Copy>,
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public CComObjectRootEx< ThreadModel >
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{
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typedef CSafeComEnum<Base, piid, T, Copy, ThreadModel> ThisClass;
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typedef CComEnumImpl<Base, piid, T, Copy> BaseClass;
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STDMETHOD(Next)(ULONG celt, T* rgelt, ULONG* pceltFetched)
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{
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//
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// Check if the return array is valid for as many elements as
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// specified. No need to explicitly check if celt is zero here, as
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// IsBadWritePtr(p, 0) is valid and returns 0.
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// celt itself will be checked in the base class method.
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//
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if ( IsBadWritePtr(rgelt, celt * sizeof(T) ) )
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{
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return E_POINTER;
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}
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//
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// Check if the return dword is bad, but if pceltFetched == NULL,
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// this may still be a valid call. pceltFetched == NULL implies that
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// celt should be equal to 1, but that will be checked in the
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// base class method.
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//
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if ( ( pceltFetched != NULL ) &&
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IsBadWritePtr(pceltFetched, sizeof(ULONG) ) )
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{
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return E_POINTER;
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}
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//
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// Everything OK so far; proceed with base class method.
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//
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return BaseClass::Next(celt, rgelt, pceltFetched);
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}
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STDMETHOD(Clone)(Base** ppEnum)
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{
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//
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// Check if the return pointer is valid.
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//
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if ( IsBadWritePtr(ppEnum, sizeof(Base *) ) )
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{
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return E_POINTER;
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}
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//
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// Everything OK so far; proceed with base class method.
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//
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return BaseClass::Clone(ppEnum);
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}
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//
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// We do not override Skip or Reset as they have no pointer arguments.
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//
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//
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// The rest of this class involves support for free thread marshaling.
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//
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BEGIN_COM_MAP( ThisClass )
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COM_INTERFACE_ENTRY_IID( *piid, BaseClass )
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COM_INTERFACE_ENTRY_AGGREGATE( IID_IMarshal, m_pFTM )
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END_COM_MAP()
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DECLARE_GET_CONTROLLING_UNKNOWN()
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HRESULT Init(T* begin, T* end, IUnknown* pUnk,
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CComEnumFlags flags = AtlFlagNoCopy)
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{
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//
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// We do not check the pointer arguments in this method because this
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// method is not exposed to the application (it is not a COM interface
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// method).
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//
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HRESULT hr;
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IUnknown * pIU = GetControllingUnknown();
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hr = CoCreateFreeThreadedMarshaler( pIU,
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& m_pFTM );
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if ( FAILED(hr) )
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{
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return hr;
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}
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return BaseClass::Init(begin, end, pUnk, flags);
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}
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CSafeComEnum()
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{
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m_pFTM = NULL;
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}
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void FinalRelease(void)
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{
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if ( m_pFTM )
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{
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m_pFTM->Release();
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}
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CComObjectRootEx< ThreadModel >::FinalRelease();
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}
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protected:
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IUnknown * m_pFTM; // pointer to free thread marshaler
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};
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#endif // _MSPENUM_H_
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